You may have seen “kumpir” on a restaurant menu before and wondered what it is. This Turkish fast food staple starts with a large potato baked in a special three-tiered oven. The potato is cooked in the lower tiers and kept warm on the top. Once done, it’s sliced lengthwise, without cutting all the way through, then the fluffy interior is mashed with butter and cheese to create a creamy filling. Many Turkish restaurants will serve their kumpir at a counter filled with toppings and sauces you can choose from. The right type of potato is key to perfecting the kumpir. “Large, floury potatoes with…